Heart disease, race and genes
GENETIC diseases translate directly into not only a major financial health
burden for countries like South Africa, but take an enormous emotional toll
too.
This was made clear by a Groote Schuur Hospital lipidology expert at the
Beyond Race conference last month, that an average heart bypass costs R120 000,
and an ordinary heart attack admission in the region of R30 000.
And consider the estimate that as many as 6,8million South Africans suffer
from genetically high cholesterol levels, which directly threatens heart
health, and the depth of the challenge is shocking.
One of Professor David Marais's areas of interest is familial
hypercholesterolaemia (FH), where high cholesterol levels are the result of
specific genetic defects. The unfortunate result is often the early
development of other problems like atherosclerosis, or narrowing of the
arteries, which translates directly into heart problems.
Marais, a specialist physician and head of the division of lipidology in
Groote Schuur's Department of Medicine, revealed to the conference yesterday
that children as young as six or seven were undergoing heart bypass surgery.
And those costs did not take into account the suffering and bereavement of
families, he said.
According to Marais, while heritable metabolic disorders certainly put
people at high-risk for disease, preventive treatment could be effective.
Recognising atherosclerosis, pancreatitits and other, rare disorders, was
important for genetic counseling as well as for public health planning.
Pointing to FH specifically, Marais said this had been diagnosed in patients
from several ancestral lines, but the highest prevalence was in Afrikaans
people. Founder effects had also been noted in Jews and Indians.
Marais yesterday showed the conference a "family tree" of a family affected
by FH, where the grandfather had lived to age 76. But by age 43 the manšs
grandson had already had five heart attacks.
In his generation, in fact, the average age of death was just 37.
The disease, he said, affected people quite young, and appeared to be
universal with the average age of first attack at 45 years, whatever the
ethnic group.
Afrikaans people here were primarily affected by the FH2 variant of the
responsible gene, which translated into heart disease at a much younger age.
But defects seen at his Cape Town clinic could also be linked to migrants
from Eastern Europe, and another group, the CT2 mutation, was a
predominantly coloured group which appeared to hail from around Mossel Bay.
The French-Canadian mutation had been identified in Indian people too, and
a Scandinavian defect had been found in several Afrikaans people.
Moving on to metabolic stressors, Marais said age definitely appeared to be
a factor, along with pregnancy, but that obesity and diabetes in both
developing and developed countries could "tip" people into dyslipidaemia.
Another factor to keep a close eye on were protease inhibitors for people
with HIV and Aids, which also translated into increased metabolic stress.
Treatment and diagnosis, he said, was hampered by limited resources,
competing healthcare pressures, a transitional population, limited public
awareness as to the severity of the problem, along with the centralised
clinics and little support.
"The perception is that it's expensive to treat, but the reality is that
often it is expensive to not treat. We need regional clinics with dietetic services, and this network of
clinics should run in conjunction with a dedicated integrated national centre of
expertise," Marais suggested.
Professor Bongani Mayosi,
head of Groote Schuur's Department of Medicine,
explained that sudden and unexpected deaths of young people, usually while
exercising, could in large part be attributed to heart muscle disease, or
cardiomyopathy.
This appeared to be caused by "electrical instability" of the heart.
In respect of genetic influences on the condition, Mayosi told delegates a
lot of work had already been done, and that it appeared that heart muscle
thickening was the result of mutations in the genes that code for "the
molecular motor of cells."
Basically, people with this condition were "working at 50% capacity"
Among Afrikaans people in South Africa, about three mutations had been found
to be responsible for two-thirds of cases. But in the rest of the world,
pinpointing the responsible mutation was not nearly so easy, and in fact
posed a formidable challenge.
More information:
 The
Beyond Race Conference was organised by the Africa Genome Education Institute -
www.africagenome.co.za
Related articles:
Race and research
Skin colour and race
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